The University of Oklahoma is immediately severing "all ties and affiliations" between the school and its local Sigma Alpha Epsilon fraternity, the university president said, and is exploring the possibility of expulsions in the wake of a video that purportedly shows members of the chapter singing a racist chant.

The video, which surfaced over the weekend, was posted to Twitter by Unheard, which describes itself as "an alliance of black students organized for change within campus administration and atmosphere." The video shows young men on a bus chanting, "There will never be a n----r at SAE."

The tweet, directed at OU president David Boren, said, "Racism is alive at The University of Oklahoma."

Boren said at a news conference Monday that he was "sickened by the video," and, "I couldn't sleep after that."

And the Tri Delta sorority announced that it is investigating the incident. In the video, Tri Delta members are seen singing with SAE members on the charter bus.

"We are deeply disappointed by the conduct of the students involved in the incident at The University of Oklahoma," the national Tri Delta sorority said in a statement. "Tri Delta expects its members to uphold the highest responsibilities of college women. The behavior documented in the video is deplorable and is in no way consistent with Tri Delta's ideals and core values. We are cooperating fully with our partners at the university as they investigate this matter."

The sorority later issued a followup statement, saying, "Members of the chapter were not pictured in the video and have not been and are not currently the subject of any investigation. We will continue to cooperate fully with our partners at the university."

The Sigma Alpha Epsilon fraternity house is seen at the University of Oklahoma in Norman, Oklahoma.

Boren said in an earlier written statement that all ties and affiliations between the school and the SAE chapter are "hereby severed."

"To those who have misused their free speech in such a reprehensible way, I have a message for you. You are disgraceful," Boren's statement read. "You have violated all that we stand for. You should not have the privilege of calling yourselves 'Sooners.' Real Sooners are not racist. Real Sooners are not bigots. Real Sooners believe in equal opportunity. Real Sooners treat all people with respect. Real Sooners love each other and take care of each other like family members.

"All of us will redouble our efforts to create the strongest sense of family and community," Boren added. "We vow that we will be an example to the entire country of how to deal with this issue. There must be zero tolerance for racism everywhere in our nation."

Boren said SAE residents would have to remove their possessions and vacate the house "by midnight tomorrow."

In fact, he said he'd be happy if the "bus-load" of students involved left school, adding that the university's legal team is exploring possible further punishment up to and including expulsion.

"As they pack their bags, I hope they think long and hard about what they've done," Boren said.

Boren called the video "heartbreaking for every member of this community."

The national SAE organization said in its own statement that it closed the Oklahoma Kappa chapter at the University of Oklahoma and suspended all of the fraternity's members -- and the members involved with the incident could have their membership privileges revoked permanently.

"We apologize for the unacceptable and racist behavior of the individuals in the video, and we are disgusted that any member would act in such a way," the online statement read. "Furthermore, we are embarrassed by this video and offer our empathy not only to anyone outside the organization who is offended but also to our brothers who come from a wide range of backgrounds, cultures and ethnicities."